I notice that fish can swim up or down really fast and wonder if they can get DS or not. someone explain that they are marine life and can adapt to it. But I think it is the law of physic that bubbles form when pressure change and no beings can be exempted from it. ( May be to certain extend but not totally.) Just like we cant immune to fire even if we burn by it many times.
Can anyone explain that? 

Fish breath in water... not air
Air is compressible/decompressible easily but not for liquid

And NO nitrogen/helium in water for them to absorb

Do some study on "Liquid breathing". That's might be the future of diving.... inhale/exhale liquid..

Quote "http://en.wikipedia.org/wiki/Perflubron"
Liquid breathing would not result in the saturation of body tissues with high pressure nitrogen or helium that occurs with the use of non-liquids, thus would reduce or remove the need for slow decompression. (This technology was dramatized in James Cameron's 1989 film The Abyss.)

Thanks Mike, the cloud/doubt is all gone!!

And NO nitrogen/helium in water for them to absorb

one question, why no N2/He in water ? I thought all gases disolved in water, just the matter of more or less, right?

this i learnt by experience..fishes are also susceptible to DCS..i dont know if some of you have been on deep sea fishing trips..when ur line caught a fish and u reeled in ur line with all ur might and at fast speed. The fish usually landed on the boat with its gut and the bladder in its mouth(literally!)..and the eyes almost popped out from its skull..

i guess the appropriate way to keep the fish alive is to reel in slowly, thus mimicking deep stops and maybe give it a few minutes of safety stop before landing it on the deck.(but to reel it in slowly, meaning to give the sharkies easy dinner)

ok, i eat fish, most of us do, at the very least.. so spare me the conservation talk, at least I fish in the most eco-friendly way..only take those that are of legal size

Ok, so fish absorb the oxygen from the water through the gills, and the O2 is absorbed by the red blood cells. So, there is no O2 in gas form. So, fish do not get decomp sickness. Fine.

  My followup question is: how about mammals and amphibians like whales, dolphins, turtles, etc, that breath fresh air? why don't they get decomp sickness? 

Catch-And-Release May Be Giving Fish The Bends

July 15, 2004

Release from: Anne McIlroy
Globe and Mail (Canada)
Sport fishing has never been a gas for the fish. But now Canadian researchers have found that fish that are caught and released may go back into the water with decompression sickness, or what divers call the bends.

Decompression sickness in humans occurs when divers surface too quickly, and nitrogen that has dissolved in their blood under pressure expands rapidly, forming bubbles that clot or damage blood vessels. It can cause pain, itching, dizziness and chest pain. Untreated, it can cause paralysis or death.

Many fishermen have suspected that fish hauled up quickly from the depths might experience similar problems, and now a Canadian researcher has found evidence they are right.

"Our results show that when fish are rapidly brought to the surface from depth, they experience the equivalent of the bends, just like humans," said Bruce Tufts, a Queen's University biologist.

Fish don't have to be caught very deep underwater to suffer from the problem. Dr. Tufts found that smallmouth bass, hooked in as little as five metres of water, show signs of the bends. He took blood samples and found that gas bubbles had formed in their bodies. There was evidence of tissue damage.

"Internally, what the fish experience is very similar to humans with the bends," Dr. Tufts said.

What is not clear is how decompression sickness affects a fish's chance of survival. In a news release, Dr. Tufts said it could be a significant conservation issue in deeper lakes across North America.

The next step is to find ways to help fish that are caught and released to recover from the bends.

"My prediction is that if they're released within a short period of time, they'll actually be able to swim back down to the right depth and they'll be fine," said Dr. Tufts, whose work is funded by the Natural Sciences and Engineering Research Council. It is to be published in a coming edition of the journal Transactions of the American Fisheries Society.

Returning the fish to depth is similar to the treatment given divers afflicted with the bends. They can be treated in decompression chambers that mimic the pressure of being deep underwater. This shrinks the nitrogen bubbles and gives the divers time to exhale the excess gas slowly.

Dr. Tufts wants to work with recreational anglers to come up guidelines for catching and releasing fish. These might include weighing fish more frequently during tournaments so they can be returned to the water more quickly.

Fish and humans aren't the only creatures that may suffer from decompression sickness.

Last year, researchers found evidence that suggested military sonar is killing whales and dolphins around the world by driving them to the surface too quickly, causing fatal cases of the bends.

There has been anecdotal evidence about decompression sickness in fish. Deep-sea fishermen have caught fish unable to right themselves in the water because their swim bladders, balloon-like sacs that help fish float, are overinflated.

what i found on the net...similar to my experience.

WoW! More and more info in this post.

I think fish will have lower chance to get decompression because not like human, we get 79% of nitrogen every new breath and the gas is forced to be absorb into blood under pressure due to gas density getting higher and our blood absorb to balance the density different.

Example,
At surface you breath in 1 liter or air containing 1000 nitrogen molecules
Under water, you breath in 1 liter of air containing 3000 nitrogen molecules
The 3000 molecules of nitrogen in lungs are more dense than the amount of nitrogen in blood, so it is absorb to balance.
When you go up slowly, the air you breath has lesser density, so the high dense of nitrogen in blood absorbed previously is released back to air.
Bend comes when high density of nitrogen in blood cannot released in time by our lungs and no where to go, become bubbles.

Fish in water will absorb gases from water surrounding. I think its blood will have almost the same amount of gas in water.
The deeper the fish go, I don't think the surrounding water have much different in the density of gases which cause the fish to absorbs in blood and cause bends when it ascent rapidly.

Hoping someone can fight my theory.